Telecommunication, cable television, and data communication systems use optical networks to rapidly convey information between remote points. In the optical networks, information is conveyed in the form of optical signals through optical fibers, which may also be referred to as a lightpath.
Software-defined networking (SDN) is a step in network virtualization and abstraction. SDN may enable a logical network entity to be instantiated automatically using software instructions. In this manner, SDN may enable flexible definitions of virtual networks. For example, using OpenFlow communications protocol managed by The Open Network Foundation (ONF), a traffic flow entity may be instantiated using an arbitrary combination of layer identifiers defined in a header space. OpenFlow may use various combinations of traffic identifiers (e.g., Internet-protocol (IP) addresses, media access controller (MAC) addresses, port addresses, etc.) at various layers to define a traffic flow. By installing and configuring packet-forwarding rules associated with the flow to physical switches, an OpenFlow controller may ensure that the traffic flow entity instantiates a path that is routed through a network including the physical switches.
FlowVisor is an example of a network virtualization layer of OpenFlow. FlowVisor may instantiate a virtual network entity (called a “slice”) by associating multiple traffic flow entities with a given slice, whereby each slice is managed by a separate tenant controller, allowing the tenant control over a portion of network traffic and a subset of the physical network. In OpenFlow, multiple flowspaces may be defined for each network switch. Each flowspace may be associated with a slice, which in turn is managed by a separate controller. FlowVisor may ensure that actions in one slice do not affect another by intercepting and rewriting OpenFlow messages.
The principles and features of SDN technologies were initially deployed with a focus on internet protocol (IP) and Ethernet networks. However, the concept of SDN may be introduced to optical networks as well. For example, the SDN concept may be applied to agile optical networks built using colorless/directionless/flex-grid reconfigurable optical add-drop multiplexers (ROADMs) and programmable transponders for multiple modulation formats. An SDN-enabled optical network may be referred to as a Software-Defined Optical Network (SDON), which may be more open, programmable, and application aware. A feature of SDON is optical network virtualization, which may enable network service providers to provision multiple coexisting and isolated virtual optical networks (VONs) over the same physical infrastructure. For example, in conventional optical networks, network services are provided in terms of lightpaths (i.e., optical network paths between given endpoints). In SDONs, network services may be provided in terms of VONs. When provisioning VONs in response to a request, different mapping patterns for mapping VONs to a physical network may be possible.
Accordingly, network services may be provided as VONs in a SDON in place of conventional lightpaths. VON provisioning may be distinguishable from conventional lightpath provisioning in certain aspects. For example, a lightpath may be a point-to-point connection, while a VON may include a network of multiple virtual nodes and virtual links. Each virtual node in a VON may be mapped to a physical node of a physical network, while each virtual link in a VON may be mapped to one or more physical links connecting the physical nodes. In certain embodiments, virtual links for a particular VON may be provisioned collectively, rather than individually. In this manner, a VON demand may be served when all virtual links have been successfully mapped to physical links under the desired criteria for the VON demand.
Furthermore, a particular lightpath may have a fixed source and destination node. In a VON, the virtual node to physical node mapping may be flexible. For example, a virtual node may be mapped to any physical node within a certain geographic area or among a certain number of specified physical nodes, as long as a resulting physical SDON slice satisfies the service-level agreement of the VON. Such flexibility may empower a network service provider to optimize resource usage and reduce service provisioning costs.
VON provisioning may generalize the concept of optical networking service from point-to-point fixed-node-pair lightpath provisioning to multi-point flexible-nodes, or group optical network slicing. Because a lightpath may be a particular instance of a VON including two virtual nodes, each with a fixed node mapping, an SDON service provider may have backward-compatibility to lightpath provisioning with little to no modification of its VON service provisioning system.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.